x86: Fix issue with PACKUSWB when the value to convert is exactly 0x00ff

[Sleigh-InSPECtor]

The PACKUSWB instruction performs a lane-wise conversion of signed 16-bit integers to 8-bit integers, saturating the results if they are out-of-range (i.e., to the range 0 to 255).

In the SLEIGH implementation of the saturation operation, if the signed 16-bit integer is exactly equal to 0x00ff it will be converted to the byte 0x00 (instead of 0xff).

The issue with the value 0x00ff in particular is that that both (sword s> 0xff:2) and (sword s< 0xff:2) are false causing neither of the conditions. In the patch I choose to change the second condition to s<= (matching the comment above the macro), however changing the first condition would also fix the issue.

e.g.:

660f67db "PACKUSWB XMM3, XMM3" with XMM3=0x00ff_00ff

• Hardware Reference (AMD CPU): { XMM3 = 0xff_ff_00_00_00_00_00_00_ff_ff }
• x86:LE:64:default (Existing): { XMM3 = 0x0 }
• x86:LE:64:default (This patch): { XMM3 = 0xff_ff_00_00_00_00_00_00_ff_ff }

(Note: The repetition of the bytes is correct because XMM3 is both the source and destination register).